Process of refining oils



Patented Mar. 1, 1927..

UNITED STATES FRANCIS JAVIER RESINES, 0F PHILADEL PHILADELPHIA,PENSYLVANIA, A CORPORA- IPROD'UCTS RECOVERY COMPANY, OF TION OFPENNSYLVANIA.

1,619,486 PATENT OFFICE.

PHIA, PENNSYLVANIA, ASSIGNOR TO BY- PROCESS OF REFINING OILS.

N 0 Drawing.

This invention relates to processes of refining oil; and it comprises aprocess of refining fatty oils of the nature of cottonseed oil wherein abody of such oil is treated With a caustic alkali solution, usuallycaustic soda, in two successive portions, one such portion being for thepurpose of neutralization and the other portion being for the purpose ofdecolorization; an immediate centrifugal separation of admixed oil andsolution following immediately upon admixture in each case; all as morefully hereinafter set forth and as claimed.

In the refining of fatty oils of the nature of cottonseed oil, it is theusual practice to admix a certain amount of caustic soda solution,agitate and allow the mixture to settle. The amount of soda solutionused is often in excess, and it may be in large excess, of the amountrequired to neutralize the free fatty acids present. This is for thereason that the caustic soda has another function besides neutralizing:that of decolorizing and clarifying. In the usual practice the oil iswarmed sufficiently to make it fluid and is then admixed with therequired amount of soda lye as determined by laboratory procedures; Themixture is agitated and is then allowed to settle for a time. This timeis never less than several hours and may go as high as several days.During this period various other actions apparently take place; onebeing a development of a structure or state of aggregation by the soapspresent; a formation of some sort of a gel. The matter settled out, orsoap stock contains soaps formed from the free fatty acids present (aswell as a certain amount of soaps formed by the saponification ofneutral oils) coloring matter, resins, etc. and also a large amount ofneutral oil entangled by the other substances present. This includedneutral oil represents a substantial loss to the oil refiner since it isnot easy to recover it in a high grade condition. Usually the soap stockis sold for soap making as it is, and the contained oil brings but a lowprice for this purpose.

In another and copending application, Serial No. 586,523, filedSeptember 6, 1922, I have described and claimed an improvement on thisusual method wherein the body of oil and alkali after agitation is notallowed to become quiescent and given time to settle Application filedSeptember 28, 1923. Serial No. 665,467.

and separate naturally but is immediately separated in a centrifugal. Byso doing, the amount of neutral oil entangled in the soap stock ismaterially reduced; being usually reduced to a negligible amount. This Ihave found is because the soaps formed by the interaction of the alkaliand the free fatty acids of the oil are at first in a structureless inga saving in neutral oil, as in my prior process, but of markedlyimproving the color of the resultant oil. By separately neutralizing anddecolorizing the latter operation is more efficient than where the twoare simultaneous. I have found that in using an excess of caustic sodaadded at once to a vegetable oil with the object of simultaneouslyeffecting neutralizing and decolorizing, the improvement in color andgrade of the-oil is not as great as where the neutralization is firsteffected, the resulting soaps separated and then further sodaadded forthe purpose of decolorizing with another separation immediatelythereafter. In practice, I first agitate a batch or body of oil in theusual way with a caustic soda solution of any of the usual strengths,say 10. Baum to 20 Baum; but I use not much more soda than the amountrequired to exactly neutralize the free fatty acids present, say notmore than 10 or 20 per cent in excess of the neutralization amount.Commonly this slight excess is much less than the amount required for asubstantial decolorization and clarification. Admixture of oil and sodaliquor is accomplished as quickly as possible, consistent'with thoroughincorporation of the two liquids. Usually not more than 15 minutes or soof agitation are required to effect an intimate incorporation althoughwith viscid oil the time may rise to 30 minutes or so. The mixture isimmediately sent to a centrifugal machine and separated at once intoneutral oil and soap stock. No opportunity is given for the developmentof structure in the soaps formed by any quiescence or period of restfollowing the incorporation agitation. The neutral oil separated is thenagitated with a further quantity of caustic soda; this time toaccomplish decolorization. Where a given amount of oil requires, say,100 parts NaOH for neutralization of the free fatty acids present andwhere it is usual to employ another 100 parts for decolorizing, I mayuse, say 120 parts of the total caustic soda in the first orneutralizing stage and the remaining 80 parts in the second orclecolorizing stage. The proportions given are merely exemplificatory,since the amount of soda required varies with every lot of oil. But inall cases I use in thefirst stage the amount required to neutralize orperhaps a slight excess and use a further quantity of caustic soda inthe second stage. amount of caustic soda I at present use in treatingcottonseed oil is usually that indicated by the regulations of theCottonseed Crushers Association. In so doing I am enabled to produce anoil with much less than the usual refining loss and of better color.

In one particular case where the refining loss with the oil undertreatment by the usual method which involves using the full quantity ofcaustic soda at once, settling, etc., was 6.4 per cent, I 'found that ontreatmentof the same oil with the same quantity of soda in two stages,with an immediate centrifugal separation at the end of each stage, therefining loss was but 3.13 per cent and the color of the oil was muchbetter than that given by the usual process.

In practical embodiments of the present The total invention I may useany of the usual apparatus for effecting the admixture of the'sodasolution and oil though, of course, I do not require the usual settlingfacilities. In effecting immediate separation of the oil from the otherbodies while I find it much better to use a centrifugal, the point ismore in a quick separation than in the use of any particular machine. Acentrifugal gives extremely rapid separation and this is what I want.The point is to effect a separation as soon as heating and agitation arediscontinued; to afford no opportunity for development of structure inthe soapsf any colloid or gel condition. Any usual alkali or alkalisolution may be employed. Ordinarily I employ caustic soda solutionbetween and Baum as is usual; but I may use caustic potash or even limeor salts of alkaline reaction. The oil treated may be any of-the usualvegetable oils.

What I claim is The process of refining and decolorizing vegetable oilswhich comprises quickly admixing with agitation such an oil with theamount of caustic alkali solution required for neutralization,separating the neutral oil from the other matters present by centrifugalaction immediately upon completion of incorporation of the alkalisolution, once more quickly admixing with agitation the oil with afurther quantity of alkali solution sufficient to decolorize the oil andonce more separating by centrifugal action immediately thereafter.

In testimony whereof, aflixed my signature.

FRANCIS JAVIER RESINES.

I have hereunto

